Aircraft noise exposure can extend miles beyond the limits of an airport. Most noise impacts occur when aircraft are on their final approach to or initial departure paths from the airport. Since there is a wide range of sensitivity to noise, the perceived extent of noise annoyance for an individual is largely dependent on his or her personal reaction to it. The noise heard at any given point on the ground can also vary widely due to a number of factors:

• Generally, older jet aircraft are louder than newer ones. New aircraft noise exposure standards must be met by the fall of 2003

• Generally, departing aircraft are louder than arriving aircraft

• Aircraft departing for distant destinations are louder than those traveling to closer destinations (aircraft with greater fuel load cannot climb as rapidly)

• An aircraft arriving or departing at night is generally perceived to be louder than the same aircraft arriving or departing during the day (a person's sensitivity to noise is greater during sleeping hours)

Weather conditions can also affect the noise level of aircraft:

• Low cloud cover may increase the noise level by reflecting back to the ground

• Pilots may be directed to avoid thunderstorm activity by flying outside normal arrival and departure routes

• Very low cloud cover may require aircraft to use an instrument landing resulting in longer approaches

Noise exposure can also change as a result of the construction of new runways and runway extensions. A fourth runway is under construction at OIA. This will result in new areas being affected by aircraft flyover activity.

Although operations at OIA and OEA have increased, noise exposure
has been reduced in many areas around these facilities. This is a result of:

• Quieter aircraft technology developed by the industry

• Mandatory requirements by the Federal government to phase out noisier aircraft

• The implementation of noise abatement procedures